共查询到20条相似文献，搜索用时 31 毫秒
1.
Production of yellow-seeded Brassica napus through interspecific crosses 总被引：12，自引：0，他引：12
Yellow‐seeded Brassica napus was developed from interspecific crosses between yellow‐seeded Brassica rapa var.‘yellow sarson’ (AA), black‐seeded Brassica alboglabra (CC), yellow‐seeded Brassica carinata (Bbcc) and black‐seeded B. napus (AACC). Three different interspecific crossing approaches were undertaken. Approaches 1 and 2 were designed directly to develop yellow‐seeded B. napus while approach 3 was designed to produce a yellow‐seeded CC genome species. Approaches 1 and 2 differed in the steps taken after trigenomic interspecific hybrids (ABC) were generated from B. carinata×B. rapa crosses. The aim of approach 1 was to transfer the yellow seed colour genes from the A to the C genome as an intermediate step in developing yellow‐seeded B. napus. For this purpose, the ABC hybrids were crossed with black‐seeded B. napus and the three‐way interspecific hybrids were self‐pollinated for a number of generations. The F7 generation resulted in the yellowish‐brown‐seeded B. napus line, No. 06. Crossing this line with the B. napus line No. 01, resynthesized from a black‐seeded B. alboglabra x B. rapa var.‘yellow sarson’ cross (containing the yellow seed colour genes in its AA genome), yielded yellow‐seeded B. napus. This result indicated that the yellow seed colour genes were transferred from the A to the C genome in the yellowish‐brown seed colour line No. 06. In approach 2, trigenomic diploids (AABBCC) were generated from the above‐mentioned trigenomic haploids (ABC). The seed colour of the trigenomic diploid was brown, in contrast to the yellow seed colour of the parental species. Trigenomic diploids were crossed with the resynthesized B. napus line No. 01 to eliminate the B genome chromosomes, and to develop yellow‐seeded B. napus with the AA genome of ‘yellow sarson’ and the CC genome of B. carinata with yellow seed colour genes. This interspecific cross failed to generate any yellow‐seeded B. napus. Approach 3 was to develop yellow‐seeded CC genome species from B. alboglabra×B. carinata crosses. It was possible to obtain a yellowish‐brown seeded B. alboglabra, but crossing this B. alboglabra with B. rapa var.‘yellow sarson’ failed to produce yellow seed in the resynthesized B. napus. The results of approaches 2 and 3 demonstrated that yellow‐seeded B. napus cannot be developed by combining the yellow seed colour genes of the CC genome of yellow‐seeded B. carinata and the AA genome of ‘yellow sarson’. 相似文献
2.
Identification and inheritance of a partially dominant gene for yellow seed colour in Brassica napus
A yellow‐seeded doubled haploid (DH) line no. 2127‐17, derived from a resynthesized Brassica napus L., was crossed with two black‐seeded Brassica cultivars ‘Quantum’ and ‘Sprint’ of spring type. The inheritance of seed colour was investigated in the F2, and BC1 populations of the two crosses and also in the DH population derived from the F1 of the cross ‘Quantum’× no. 2127‐17. Seed colour analysis was performed with the colorimeter CR‐300 (Minolta, Japan) together with a visual classification system. The immediate F1 seeds of the reciprocals in the two crosses had the same colour as the self‐pollinated seeds of the respective black‐ and yellow‐seeded female parents, indicating the maternal control of seed colour. The F1 plants produced yellow‐brown seeds that were darker in colour than the seeds of no. 2127‐17, indicating the partial dominance of yellow seed over black. In the segregating BC1 progenies of the two crosses, the frequencies of the black‐ and yellow‐seeded plants fit well with a 1 : 1 ratio. In the cross with ‘Quantum’, the frequencies of yellow‐seeded and black‐seeded plants fit with a 13 : 3 ratio in the F2 progeny, and with a 3 : 1 ratio in the DH progeny. However, a 49 : 15 segregation ratio was observed for the yellow‐seeded and black‐seeded plants in the F2 progeny of the cross with ‘Sprint’. It was postulated from these results that seed colour was controlled by three pairs of genes. A dominant yellow‐seeded gene (Y) was identified in no. 2127‐17 that had epistatic effects on the two independent dominant black‐seeded genes (B and C), thereby inhibiting the biosynthesis of seed coat pigments. 相似文献
3.
Two yellow‐seeded white‐petalled Brassica napus F7 inbred lines, developed from interspecific crosses, containing 26–28% emcic acid and more than 40 μmol glucosinolates (GLS)/g seed were crossed with two black/dark brown seeded B. napus varieties of double low quality and 287 doubled haploid (DH) lines were produced. The segregation in the DH lines indicated that three to four gene loci are involved in the determination of seed colour, and yellow seeds are formed when all alleles in all loci are in the homozygous recessive state. A dominant gene governed white petal colour and is linked with an erucic acid allele that, in the homozygous condition, produces 26–28% erucic acid. Four gene loci are involved in the control of total GLS content where low GLS was due to the presence of recessive alleles in the homozygous condition in all loci. From the DH breeding population a yellow‐seeded, yellow‐petalled, zero erucic acid line was obtained. This line was further crossed with conventional B. napus varieties of double low quality and, following pedigree selection, a yellow seeded B. napus of double low quality was obtained. The yellow seeds had higher oil plus protein content and lower fibre content than black seeds. A reduction of the concentration of chromogenic substances was found in the transparent seed coat of the yellow‐seeded B. napus. 相似文献
4.
Inheritance of petal colour and its independent segregation from seed colour in Brassica rapa 总被引：1，自引：0，他引：1
The inheritance of petal (flower) colour and seed colour in Brassica rapa was investigated using two creamy‐white flowered, yellow‐seeded yellow sarson (an ecotype from Indian subcontinent) lines, two yellow‐flowered, partially yellow‐seeded Canadian cultivars and one yellow‐flowered, brown‐seeded rapid cycling accession, and their F1, F2, F3 and backcross populations. A joint segregation of these two characters was examined in the F2 population. Petal colour was found to be under monogenic control, where the yellow petal colour gene is dominant over the creamy‐white petal colour gene. The seed colour was found to be under digenic control and the yellow seed colour (due to a transparent coat) genes of yellow sarson are recessive to the brown/partially yellow seed colour genes of the Canadian B. rapa cvs.‘Candle’ and ‘Tobin’. The genes governing the petal colour and seed colour are inherited independently. A distorted segregation for petal colour was found in the backcross populations of yellow sarson × F1 crosses, but not in the reciprocal backcrosses, i.e. F1× yellow sarson. The possible reason is discussed in the light of genetic diversity of the parental genotypes. 相似文献
5.
The effect of genome composition and cytoplasm on petal colour was studied in Brassica. Three accessions of yellow‐petalled B. rapa (2n= 20, AA) were crossed with a white‐petalled B. oleracea var. alboglabra (2n= 18, CC) and with three cream‐yellow‐petalled B. oleracea var. gongylodes (2n= 18, CC) to produce resynthesized B. napus (2n= 38, AACC or CCAA) and sesquidiploids (2n= 29, AAC or CAA). Petal colour was measured with a Hunter automatic colour difference meter. The results revealed that petal colour in Brassica is controlled by nuclear genes and by cytoplasmic factors. Additive and epistatic gene effects were involved in the action of nuclear genes. When crosses were made between yellow‐petalled B. rapa and white‐petalled B. oleracea var. alboglabra, significant additive, epistatic and cytoplasmic effects were found. White petal colour was partially epistatic over yellow petal colour. When crosses were made between yellow‐petalled B. rapa and cream‐yellow‐petalled B. oleracea var. gongylodes, only epistatic effects were detected. Yellow petal colour was epistatic over cream‐yellow. 相似文献
6.
Inheritance of seed colour in Brassica campestris L. and breeding for yellow-seeded B. napus L. 总被引：3，自引：0，他引：3
Summary Seed colour inheritance was studied in five yellow-seeded and one black-seeded B. campestris accessions. Diallel crosses between the yellow-seeded types indicated that the four var. yellow sarson accessions of Indian origin had the same genotype for seed colour but were different from the Swedish yellow-seeded breeding line. Black seed colour was dominant over yellow. The segregation patterns for seed colour in F2 (Including reciprocals) and BC1 (backcross of F1 to the yellow-seeded parent) indicated that the black seed colour was conditioned by a single dominant gene. Seed colour was mainly controlled by the maternal genotype but influenced by the interplay between the maternal and endosperm and/or embryonic genotypes. For developing yellow-seeded B. napus genotypes, resynthesized B. napus lines containing genes for yellow seed (Chen et al., 1988) were crossed with B. napus of yellow/brown seeds, or with yellow-seeded B. carinata. Yellow-seeded F2 plants were found in the crosses that involved the B. napus breeding line. However, this yellow-seeded character did not breed true up to F4. Crosses between a yellow-seeded F3 plant and a monogenomically controlled black-seeded B. napus line of resynthesized origin revealed that the black-seeded trait in the B. alboglabra genome was possibly governed by two independently dominant genes with duplicated effect. Crossability between the resynthesized B. napus lines as female and B. carinata as male was fairly high. The sterility of the F1 plants prevented further breeding progress for developing yellow-seeded B. napus by this strategy. 相似文献
7.
Yellow seeded Brassica napus was developed through interspecific crosses with the two mustard species, B. juncea and B. carinata. The objective of these two interspecific crosses was the introgression of genes for yellow seed colour from the A genome of B. juncea and C genome of B. carinata into the A and C genomes of B. napus, respectively. The interspecific F1 generations were backcrossed to B. napus in an attempt to eliminate B genome chromosomes and to improve fertility. Backcross F2 plants of the (B. napus×B. juncea) ×B. napus cross were then crossed with backcross F2 plants of the (B. napus×B. carinata) ×B. napus cross. The objective of this intercrossing was to combine the A and C genome yellow seeded characteristics of the two backcross populations into one genotype. The F2 generation of the backcross F2 intercrosses was grown in the field, plants were individually harvested and visually rated for seed colour. Ninety-one yellow seeded plants were identified among the 4858 plants inspected. This result indicated that the interspecific crossing scheme was successful in developing yellow seeded B. napus. 相似文献
8.
A yellowish brown‐seeded Brassica alboglabra was resynthesized from a (B. alboglabra×Brassica carinata) ×B. alboglabra cross, followed by self‐pollination. The resynthesized B. alboglabra lost the allele of the isozymic locus glucosephosphate isomerase‐2 (GPI‐2) from natural B. alboglabra, which was replaced by an allele from the corresponding genome in B. carinata. A simple Mendelian segregation of these two alleles was observed in the F2 population of a natural × resynthesized B. alboglabra cross. Furthermore, these two alleles segregated independently from the seed colour. 相似文献
9.
Anna Stein Benjamin Wittkop Liezhao Liu Christian Obermeier Wolfgang Friedt Rod J. Snowdon 《Plant Breeding》2013,132(4):382-389
A major quantitative trait locus (QTL) influencing seed fibre and colour in Brassica napus was dissected by marker saturation in a doubled haploid (DH) population from the black‐seeded oilseed rape line ‘Express 617’ crossed with a yellow‐seeded B. napus line, ‘1012–98’. The marker at the peak of a sub‐QTL with a strong effect on both seed colour and acid detergent lignin content lay only 4 kb away from a Brassica (H+)‐ATPase gene orthologous to the transparent testa gene AHA10. Near the peak of a second sub‐QTL, we mapped a copy of the key phenylpropanoid biosynthesis gene cinnamyl alcohol dehydrogenase, while another key phenylpropanoid biosynthesis gene, cinnamoyl co‐a reductase 1, was found nearby. In a cross between ‘Express 617’ and another dark‐seeded parent, ‘V8’, Bna.CCR1 was localized in silico near the peak of a corresponding seed fibre QTL, whereas in this case Bna.CAD2/CAD3 lay nearby. Re‐sequencing of the two phenylpropanoid genes via next‐generation amplicon sequencing revealed intragenic rearrangements and functionally relevant allelic variation in the three parents. 相似文献
10.
The inheritance of siliqua locule number and seed coat colour in Brassica juncea was investigated, using three lines each of tetralocular brown seeded and bilocular yellow seeded. Three crosses of tetralocular brown seeded × bilocular yellow seeded lines were attempted and their F1, F2 and backcross generations were examined for segregation of these two traits. Brown seed colour and bilocular siliqua characters were found to be dominant over yellow seed and tetralocular siliqua, respectively. Chi‐square tests indicated that each trait is controlled by different sets of duplicate pairs of genes. Bilocular siliquae or brown seeds can result from the presence of either of two dominant alleles, whereas tetralocular siliquae or yellow seeds are produced when alleles at both loci are recessive. A joint segregation analysis of F2 data indicated that the genes governing siliqua locule number and seed colour were inherited independently. 相似文献
11.
Six accessions belonging to four subspecies of Brassica rapa, including three accessions of B. rapa subsp. sylvestris, were crossed with B. oleracea subsp. alboglabra in order to develop a series of synthetic B. napus lines with a common C genome but contrasting A genomes. Different A genomes had significant effects on the efficiency of B. napus resynthesis and the sexual compatibility of the synthetic lines with oilseed rape cultivars. The synthetic lines were used to investigate the effect of A genome substitution on the resistance of B. napus to infection by Leptosphaeria maculans, and to explore the potential for the use of wild forms of B. rapa in oilseed rape breeding programmes. Synthetic lines derived from two wild accessions of B. rapa, and their F1 hybrids with oilseed rape cultivars, expressed high levels of resistance to L. maculans in glasshouse experiments. One of these lines also expressed high levels of resistance in field experiments in England and Australia when exposed to a genetically diverse pathogen population. All other synthetic lines and cultivars were highly susceptible in both glasshouse and field experiments. F1 hybrids between oilseed rape cultivars and synthetic lines derived from B. rapa subsp. chinensis were significantly more susceptible than either parent. 相似文献
12.
M. Habibur Rahman Rick A. Bennett Rong-Cai Yang Berisso Kebede Mohan R. Thiagarajah 《Euphytica》2011,177(3):365-374
The oilseed Brassica rapa flowers and matures earlier than B. oleracea, as well as their amphidiploid B. napus. Therefore, earliness of B.
rapa has been investigated as a source of variation for earliness in B. napus breeding programs. Variation for days to flower exists in B. oleracea; however, its earliest flowering variant B. alboglabra flowers 2–3 weeks later than B. napus. We hypothesized that the C genome of B. alboglabra carries alleles for early flowering which are different from the C-genome alleles of B. napus; and these alleles can be used for the improvement of B. napus. To test this, we examined flowering time in pedigree and DH populations from two B. napus × B. alboglabra crosses. A B. napus line with about a week earlier flowering than the B. napus parent was achieved through reconstitution of its C genome following pedigree selection. Introgression of the B. alboglabra allele in the early flowering pedigree lines is also evident from the presence of B. alboglabra-specific SSR alleles in this line. However, application of doubled haploidy failed to generate any line that flowered earlier
than the B. napus parent, which is probably due to the difficulty of obtaining large numbers of euploid B. napus DH lines from this interspecific cross. Thus, we demonstrate that a trait of the diploid species, which apparently looks
undesirable, might in fact be highly valuable for the improvement of amphidiploids; and knowledge from this research can also
be applied for other traits. 相似文献
13.
A diversity arrays technology (DArT) map was constructed to identify quantitative trait loci (QTL) affecting seed colour, hairy leaf, seedling anthocyanin, leaf chlorosis and days to flowering in Brassica rapa using a F2 population from a cross between two parents with contrasting traits. Two genes with dominant epistatic interaction were responsible for seed colour. One major dominant gene controls the hairy leaf trait. Seedling anthocyanin was controlled by a major single dominant gene. The parents did not exhibit leaf chlorosis; however, 32% F2 plants showed leaf chlorosis in the population. A distorted segregation was observed for days to flowering in the F2 population. A linkage map was constructed with 376 DArT markers distributed over 12 linkage groups covering 579.7 cM. The DArT markers were assigned on different chromosomes of B. rapa using B. rapa genome sequences and DArT consensus map of B. napus. Two QTL (RSC1‐2 and RSC12‐56) located on chromosome A8 and chromosome A9 were identified for seed colour, which explained 19.4% and 18.2% of the phenotypic variation, respectively. The seed colour marker located in the ortholog to Arabidopsis thaliana Transparent Testa2 (AtTT2). Two QTL RLH6‐0 and RLH9‐16 were identified for hairy leaf, which explained 31.6% and 20.7% phenotypic variation, respectively. A single QTL (RSAn‐12‐157) on chromosome A7, which explained 12.8% of phenotypic variation was detected for seedling anthocyanin. The seedling anthocyanin marker is found within the A. thaliana Transparent Testa12 (AtTT12) ortholog. A QTL (RLC6‐04) for leaf chlorosis was identified, which explained 55.3% of phenotypic variation. QTL for hairy leaf and leaf chlorosis were located 0–4 cM apart on the same chromosome A1. A single QTL (RDF‐10‐0) for days to flowering was identified, which explained 21.4% phenotypic variation. 相似文献
14.
Brassica napus L. was resynthesized through interspecific hybridization between B. alboglabra Bailey and B campestris L. with the objective or developing yellow-seeded forms of this species. For hybridization, one black-seeded form and one light brown-seeded form of B. alboglabra (a subordinate of B. oleracea) and one brown and ten yellow-seeded forms of B. campestris were chosen as parents. Crosses with B. alboglabra as the female parent were more successful than crushes with B. campestris as female. The use of the embryo rescue culture technique greatly increased the number of surviving hybrid embryos. Colchicine treatment was required for doubling the chromosome number of the amphihaploid hybrid plants. In the newly-resynthesized rape forms, the white petal of B. alboglabra was partially epistatic over the yellow petal of B. campestris. The self compatibility of B. alboglabra was hypostatic to the self incompatibility of B. campestris. The black-seeded character of B. alboglabra and the brown-seeded character of B. campestris were completely eptstatic over the yellow-seeded character of B. campestris and the light brown-seeded character of B. alboglabra. Implications of the results from this study in breeding yellow-seeded B. napus are discussed. 相似文献
15.
Y. Kaneko S. W. Bang J. Torii-Abe R. B. Eduardo Y. Matsuzawa C. Jung 《Plant Breeding》2003,122(5):450-452
Six haploid plants of radish were obtained via alien monosomic addition lines (2n = 19). One plant was derived from anther culture of an Raphanus sativus‐Brassica oleracea addition line, one plant from the selected smaller seed of an R. sativus‐Sinapis arvensis addition line and four plants from an R. sativus‐B. rapa addition line. During metaphase I of pollen mother cells, two plants exhibited the chromosome pairing of (0‐3)II+ (3‐9)I, three showed (0‐1)III + (0‐3)II + (3‐9)I and the remaining plant (0‐2)II + (5‐9)I. Trivalents seemed to be formed by the pairing between two larger chromosomes and the smaller one with somewhat loose pairing. All haploid plants were inferior to the radish cv. ‘Shogoin’ (2n = 18) with respect to vegetative growth. Their flowers were smaller, with sterile pollen grains, but a few normal flowers with fertile pollen sporadically developed and then produced a few seeds. It is suggested that the radish genome (R, n = 9) might comprise three pairs of homoeologous chromosomes, with the remaining three chromosomes carrying the homologous region(s) that results in a trivalent formation. 相似文献
16.
B. R. Choudhary 《Plant Breeding》2008,127(2):211-213
The inheritance of siliqua orientation and seed coat colour in Brassica tournefortii was investigated using four genotypes varying in these two characters. The F1, F2 and backcross generations of two crosses were used for studying the segregation pattern of the traits. The plants were classified for seed colour as having brown or yellow seeds and for siliqua orientation as having upright, semi‐spread or spread siliqua. Seed colour was found to be under monogenic control with brown being dominant over yellow. Siliqua orientation was under digenic polymeric gene action: upright siliqua was produced by the presence of two dominant genes and spread siliqua by two recessive genes. The absence of even a single dominant gene resulted in a third type of siliqua orientation, semi‐spread siliqua. 相似文献
17.
Cytological observation of anther structure and genetic investigation of a new type of cytoplasmic male sterile 0A193‐CMS in Brassica rapa L. 
下载免费PDF全文
下载免费PDF全文 Cytoplasmic male sterility (CMS), a maternally transmitted failure in pollen formation, is an effective pollination control system in hybrid rapeseed (Brassica napus) breeding. However, CMS is not widely used in the related oilseed species Brassica rapa. In the past years, several male sterile plants have been isolated from the B. rapa landrace ‘0A193’, collected in Shaanxi, China, in 2011. It is noteworthy that the fertility expression of 0A193‐CMS was affected by temperature. In contrast to pol CMS, fertility tests with 18 B. rapa and 9 B. napus accessions suggest that a different system of maintaining and restoring is responsible for the observed phenotype. Further on, genetic investigation evidenced that fertility of 0A193‐CMS is controlled by both cytoplasmic and one pair of nuclear recessive genes. Interestingly, plants of the 0A193‐CMS type possess a highly specific fragment of the mitochondrial gene orf222, a crucial regulator of male sterility in nap CMS. Our study broadens the CMS resources in B. rapa and provides a highly applicable alternative to pol CMS and ogu CMS for hybrid breeding production. 相似文献
18.
Genetic stability and maintenance of Raphanus sativus lines with an added Brassica rapa chromosome 总被引：2，自引：0，他引：2
The genetic stability and maintenance of Raphanus sativus‐Brassica rapa monosomic chromosome addition lines (a‐h‐types MALs, 2n = 19, BC2), developed by backcrossing the synthesized amphidiploid Raphanobrassica (Raphanus sativus × Brassica rapa, 2n = 38, RRAA) with R. sativus cv. ‘Shogoin’ (2n = 18, RR), was investigated. Transmission of the added alien chromosome through selected smaller seeds (SSS) and the inheritance of morphological traits and random amplified polymorphic DNA (RAPD)‐specific markers together with meiotic chromosome configuration and seed fertility were also investigated for three successive generations (BC3 to BC5). The distinctive traits and the RAPD‐specific markers of the eight types of MAL were substantially inherited and stably maintained throughout three generations, although a few variant plants (2n =18) resembling MALs (2n = 19) and hyperploidal plants (2n = 26 and 2n = 37) were generated in the earlier generations of BC3 and BC4 in comparison with BC5. The average transmission rates for three generations ranged from 26% for both the b‐type and the d‐type to 44% for the e‐type through SSS. On the other hand, the transmission rates through randomly selected seeds (RSS) were lower, ranging from 6.5% for the f‐type to 23.5% for the b‐type. In meiosis, more than 90% of PMCs showed the 9II +1I pairing configuration at metaphase I throughout three generations. For seed fertility, when backcrossed with the radish cv. ‘Shogoin’, the values were approximately 180% to 500% with the mode around 300% with the seed harvested from a pod increasing with the advancing generations. Genetic recombination between the radish chromosomes and the added chromosome is probably rare, suggesting that the added chromosome is mostly maintained unaltered in the background of the radish genome. 相似文献
19.
Condensed tannins (proanthocyanidins, PAs) in the seed meal of oilseed rape can potentially have a negative impact on non-ruminant
livestock nutrition, particularly because of their ability to form indigestible, astringent or bitter-tasting complexes with
proteins. One option to overcome this problem is the breeding of oilseed rape varieties with reduced condensed tannins in
the seed coat. This might be achievable via selection of genotypes with thinner seed coats and consequently reduced condensed
tannin accumulation (seed coat structural cell mutants), or alternatively by selection of genotypes with reduced biosynthesis
of condensed tannins (flavonoid biosynthesis mutants). Both types of transparent testa (TT) mutants are well-characterised
in Arabidopsis; however the genetic basis of the yellow-seed trait in the polyploid genome of rapeseed is still not completely understood.
In this study, genetic and chemical analyses of PAs were performed in 166 doubled haploid (DH) rapeseed lines from the segregating
Brassica napus doubled haploid population YE2-DH (black seed × yellow seed). Using these analyses, the relationship between seed colour
and PA fractions in B. napus was investigated with a view to improving the rapeseed meal quality. Proanthocyanidin contents were estimated by vanillin
and HPLC assays and the obtained values were used to identify quantitative trait loci. Closely linked molecular markers that
were identified during this study for the target traits (seed colour, condensed tannins) can be valuable tools for breeding
of new oilseed rape cultivars with reduced levels of antinutritive PA compounds. 相似文献
20.
Genotypic Variation for Tolerance to Transient Drought During the Reproductive Phase of Brassica rapa 下载免费PDF全文
下载免费PDF全文 Y. M. Guo N. C. Turner S. Chen M. N. Nelson K. H. M. Siddique W. A. Cowling 《Journal of Agronomy and Crop Science》2015,201(4):267-279
Brassica rapa L. is a genetically diverse parent species of the allotetraploid species, oilseed rape (B. napus) and a potential source of drought tolerance for B. napus. We examined the effect of a 13‐day drought stress period during the early reproductive phase, relative to a well‐watered (WW) control, on subsequent growth and development in nine accessions of B. rapa and one accession of Brassica juncea selected for their wide morphological and genetic diversity. We measured leaf water potential, stomatal conductance, water use, and leaf and bud temperatures during the stress period and aboveground dry weight of total biomass at maturity. Dry weight of seeds and reproductive tissue were not useful measures of drought tolerance due to self‐incompatibility in B. rapa. The relative total biomass (used as the measure of drought tolerance in this study) of the 10 accessions exposed to drought stress ranged from 47 % to 117 % of the WW treatment and was negatively correlated with leaf‐to‐air and bud‐to‐air temperature difference when averaged across the 13‐day stress period. Two wild‐type (B. rapa ssp. sylvestris) accessions had higher relative total and non‐reproductive biomass at maturity and cooler leaves and buds than other types. We conclude that considerable genotypic variation for drought tolerance exists in B. rapa and cooler leaves and buds during a transient drought stress in the early reproductive phase may be a useful screening tool for drought tolerance. 相似文献