Progress 09/25/03 to 08/31/05
Outputs
4d Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Montana State University. Additional details of research can be found in the report for the parent CRIS 5348-21000-014-00D, Germplasm Enhancement, Genetics and Disease Management of Cool Season Food Legumes. The objective of the project was to determine the genetic basis of cold tolerance in the Afghanistan type of pea. A population of 90 F2-derived recombinant inbred lines (RILs) have been developed from the cross PI220174 x A1078-239. The former is a line collected in Afghanistan and possessing the Afghanistan genotype. The latter is a multiple marker line originally developed by Dr. G. A. Marx. It does not possess exceptional cold tolerance or winter hardiness. Each of the 90 recombinant inbred lines has been genotyped for approximately 30 selected genetic markers that provide good coverage of linkage groups I, III, IV, V, VI and much of VII
(there remains one gap on LG VII). Only two markers have been scored on LG II (one at each end), and we are still screening the parents for additional markers on this linkage group. The lines will be scored for cold tolerance and winter hardiness this coming winter, and a QTL analysis of these data will be performed using the 30 markers already available plus another 10 markers that should complete coverage on linkage groups II and VII. If additional lines are necessary to confirm results, we have another two F2-derived recombinant inbred line populations from the crosses PI 220174 x CMG and Majoret x PI 220174, as well as two backcross populations: [PI 220174 x CMG] x CMG and [PI 125840 x Sparkle] x Sparkle to work with. Also included under this project is a gene discovery investigation of Pisum sativum ssp. abyssinicum. A series of backcross recombinant inbred lines (BC-RILs) were developed for this part of the project. BC-RILs were used instead of the usual F2-derived RILs because
of the relatively high sterility observed in the F1s from crosses between P. sativum ssp. sativum and P. sativum ssp. abyssinicum. Over 100 markers have been mapped in the BC-RILs. These markers have been used to identify QTLs for plant height, total root area, flowering time and leaf shape.
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Progress 10/01/03 to 09/30/04
Outputs
4. What were the most significant accomplishments this past year? D. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and Montana State University. Additional details of research can be found in the report for the parent CRIS 5348-21000-014-00D, Germplasm Enhancement, Genetics and Disease Management of Cool Season Food Legumes. An analysis of the genetic basis of traits segregating in progeny derived from Pisum sativum ssp. sativum x P. s. ssp abyssinicum indicates that the Abyssinicum pea is a combination of primitive and domesticated characters. Primitive characters include the presence of anthocyanins, black pigmented hilum, intermediate growth habit, and small root/shoot ratio. Domesticated traits include indehiscent pod, medium seed size, early blooming, broad leaflets, and lack of seed dormancy. The Abyssinicum pea also possesses a set of traits (serrate leaflets, one pair of leaflets per leaf, several
specific molecular markers) that uniquely define it taxonomically. Plant height, leaf size and shape, flowering time and root/shoot ratio all displayed polygenic inheritance in the populations studied. Two major genes were found to influence plant height and these appeared to be the same as two identified as affecting height in P. s. ssp. elatius x P. s. ssp sativum populations. One of these genes (gibberellin 3-oxidase) also appeared to influence leaf size and total root area. The difference in total root area between the Abyssinicum pea and cultivated pea was also influenced by a gene on linkage group II. The genotype for flowering genes in Abyssinicum pea was determined to be Lf, Sn, hr, E, with a fifth locus appearing to be responsible for the relatively early flowering node for this genotype. The results of our analysis of traits influenced by more than one locus paralleled that of single gene characters in that P. s. ssp. abyssinicum was found to be fixed for a mixture of P. s.
ssp. elatius and P. s. ssp. sativum alleles, as well as possessing certain 'unique' alleles not identified in the other two taxa. The loci controlling the polygenic traits analyzed are distributed over six of the seven linkage groups. These results support the hypothesis that the Abyssinicum pea diverged from the typical cultivated pea germplasm several thousand years ago after the loss of pod dehiscence and increase in seed size but before fixation of many other traits found in modern cultivars.
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