Growth, seed development and genetic analysis in wild type and Def mutant of Pisum sativum L

Abstract

BackgroundThe def mutant pea (Pisum sativum L) showed non-abscission of seeds from the funicule. Here we present data on seed development and growth pattern and their relationship in predicting this particular trait in wild type and mutant lines as well as the inheritance pattern of the def allele in F2 and F3 populations.FindingsPod length and seed fresh weight increase with fruit maturity and this may affect the abscission event in pea seeds. However, the seed position in either the distal and proximal ends of the pod did not show any difference. The growth factors of seed fresh weight (FW), width of funicles (WFN), seed width (SW) and seed height (SH) were highly correlated and their relationships were determined in both wild type and def mutant peas. The coefficient of determination R2 values for the relationship between WFN and FW, SW and SH and their various interactions were higher for the def dwarf type. Stepwise multiple regression analysis showed that variation of WFN was associated with SH and SW. Pearson's chi square analysis revealed that the inheritance and segregation of the Def locus in 3:1 ratio was significant in two F2 populations. Structural analysis of the F3 population was used to confirm the inheritance status of the Def locus in F2 heterozygote plants.ConclusionsThis study investigated the inheritance of the presence or absence of the Def allele, controlling the presence of an abscission zone (AZ) or an abscission-less zone (ALZ) forming in wild type and mutant lines respectively. The single major gene (Def) controlling this phenotype was monogenic and def mutants were characterized and controlled by the homozygous recessive def allele that showed no palisade layers in the hilum region of the seed coat.

Pea (Pisum sativum L.) in the Genomic Era

“…In pea seeds the Def (Development funiculus) locus defines an abscission layer between the funiculus and the hilum at maturity. A spontaneous mutation at this locus results in the seed failing to abscise from the funicle which is common in wild types [229]. Although the abscission of pea seeds from the funicle helps ensure effective dispersal of seeds, significant loss of seeds can occur if late rains followed by high temperatures and dry winds cause the pods to split open.…”

Primary and Secondary Abscission in Pisum sativum and Euphorbia pulcherrima—How Do They Compare and How Do They Differ?

“…In Arabidopsis the pedicels do not abscise and there is only a rudiment of an AZ left at the base of the pedicles in this species, showing that AZ in Arabidopsis petals are primary (pre-defined). When we failed to find ida in poinsettia, we turned to the AZL def mutants in pea (Ayeh et al, 2011 ). The pea system demonstrated expression of highly conserved poinsettia sequences involved in pea abscission.…”

“…The four lines of pea ( P. sativum L.) seeds (JI 116, JI 2822, JI 1184, and JI 3020) in this study were selected based on the presence of specific alleles at the Def locus, which control the detachment of the seed from the funiculus (Ayeh et al, 2009 , 2011 ). Two wild types (WT) with the Def locus and two def mutant pea seeds were kindly supplied from the John Innes Pisum Collection Ayeh et al ( 2009 ).…”

“…Similarly, the primary abscission zones of the wild type peas (JI 116 and JI 2822), as well as the two def mutant peas (JI 1184 and JI 3020) were harvested and given the same fixation and embedding as the poinsettias above. The def gene is a single locus gene (Ayeh et al, 2011 ) and the abscission zone between the funiculus and the pea was characterized (Ayeh et al, 2009 ) in both mutants (with abscission-less zones) and both tall and dwarf wild types.…”

“…These mutants were the tools to elucidate upon the process of abscission in peas (Ayeh, 2008 ). That study concluded that the def gene is a single locus gene (Ayeh et al, 2011 ) and the abscission zone between the funiculus and the pea was characterized (Ayeh et al, 2009 ) in both mutants (with abscission-less zones) and tall and dwarf wild types. Pea has primary abscission, with the AZ clearly defined from the onset in the wild types and only the distorted abscission-less zone in the mutants.…”