Junhong Ma

Diversity of seed protein among the Australian narrow-leafed lupin (Lupinus angustifolius L.) cultivars

Narrow-leafed lupin (NLL) is one of the major legume crops in Australian farming systems which is largely used as animal feed. Several modern cultivars have been developed through breeding making NLL feasible for use as human food. Significant health benefits have been recognised for NLL. The current study characterised protein polymorphism among 25 Australian cultivars through mass spectrometry (MALDI-TOF) with the aim of developing molecular breeding strategies to improve protein quality and content. A total of 364 seed protein mass peaks were clearly identified by MALDI-TOF and 50 protein mass peaks were cultivar specific. In addition, 9 protein mass peaks were found present in all cultivars and 61 protein mass peaks present in 2-3 cultivars only. Phylogenic analysis based on the protein profile categorised the cultivars into 2 major groups, which are broadly supported by pedigree information. The low proportion (2.4%) of common protein mass peaks among the cultivars suggested a high level of diversity in seed protein of NLL.

An improved MALDI-TOF mass spectrometry procedure and a novel DNA marker for identifying over-expressed Bx7 glutenin protein subunit in wheat

Wheat bread-making quality is mainly determined by glutenin proteins in the grain, which exist in a wide range of variable alleles with differential influence on processing attributes. A recently identified allele, Bx7 over-expression (Bx7(oe) ), has been showing highly significant positive effects on wheat dough strength over the normally expressed Bx7 allele. SDS-PAGE and normal RP-HPLC procedures failed to separate the two alleles. In the current study, an extensively optimised MALDI-TOF based procedure and a refined DNA based marker for efficiently differentiating Bx7(oe) from normal Bx7 allele were established. Results indicated that the MALDI-TOF procedure is cost effective, high throughput, and proven reliable, while the refined PCR marker only amplifies Bx7(oe) allele, a clear advantage over the previously developed codominant marker.

High frequency of unusual high molecular weight glutenin alleles in 232 tetraploid durum wheat accessions (Triticum turgidum L. ssp. durum Desf)

A total of 232 accessions of tetraploid species, durum wheat (Triticum turgidum L. ssp. durum Desf., 2n=4x=28, AABB) with a widespread origin of various countries were used in this study. Their high molecular weight glutenin subunit (HMW-GS) composition was identified by Matrix-assisted laser desorption/ionization time-of-flight Mass Spectrometry (MALDI-TOF-MS). Among all accessions analyzed, 194 were homogeneous for HMW-GS, 38 were heterogeneous, and 62 possessed unusual or new subunits. The results revealed a total of 43 alleles, including 5 at Glu-A1 and 38 at Glu-B1, resulting in 60 different allele combinations. The Glu-B1 locus displayed higher variation compared with Glu-A1. Glu-A1c (55.2%) and Glu-B1aj (17.7%) were the most frequent alleles at Glu-A1 and Glu-B1, respectively. Two allele types (“null” and 1) at the Glu-A1 locus and three allele types (7OE + 8, 14+15, 8) at the Glu-B1 locus appeared to be the common types in the 232 accessions. A total of 23 new alleles represented by unusual subunits were detected at the Glu-A1 and the Glu-B1 locus.