Phytic acid (PA) acts as a storehouse for the majority of the mineral phosphorous (P) in maize; ~80% of the total P stored as phytate P is not available to monogastric animals and thereby causes eutrophication. In addition, phytic acid chelates positively charged minerals making them unavailable in the diet. The mutant lpa1-1 allele reduces PA more than the wild-type LPA1 allele. Further, mutant gene opaque2 (o2) enhances lysine and tryptophan and crtRB1 enhances provitamin-A (proA) more than wild-type O2 and CRTRB1 alleles, respectively. So far, the expression pattern of the mutant lpa1-1 allele has not been analysed in maize genotypes rich in lysine, tryptophan and proA. Here, we analysed the expression pattern of wild and mutant alleles of LPA1, O2 and CRTRB1 genes in inbreds with (i) mutant lpa1-1, o2 and crtRB1 alleles, (ii) wild-type LPA1 allele and mutant o2 and crtRB1 alleles and (iii) wild-type LPA1, O2 and CRTRB1 alleles at 15, 30 and 45 days after pollination (DAP). The average reduction of PA/total phosphorous (TP) in lpa1-1 mutant inbreds was 29.30% over wild-type LPA1 allele. The o2 and crtRB1-based inbreds possessed ~two-fold higher amounts of lysine and tryptophan, and four-fold higher amounts of proA compared to wild-type alleles. The transcript levels of lpa1-1, o2 and crtRB1 genes in lpa1-1-based inbreds were significantly lower than their wild-type versions across kernel development. The lpa1-1, o2 and crtRB1 genes reached their highest peak at 15 DAP. The correlation of transcript levels of lpa1-1 was positive for PA/TP (r = 0.980), whereas it was negative with inorganic phosphorous (iP) (r = −0.950). The o2 and crtRB1 transcripts showed negative correlations with lysine (r = −0.887) and tryptophan (r = −0.893), and proA (r = −0.940), respectively. This is the first comprehensive study on lpa1-1 expression in the maize inbreds during different kernel development stages. The information generated here offers great potential for comprehending the dynamics of phytic acid regulation in maize.

Hybrid seed production technology requires cross pollination between parents of choice. Several physical and chemical techniques including manual or mechanical emasculation and male gametocide chemicals have been introduced each with respective disadvantages. Easy and quick technique such as environment sensitive male sterility is effected by environmental irregularities. Identification of commercial use of genetic means of male sterility systems like GMS and CGMS have brought revolutionary benefits to hybrid seed industry in many crops to feed an ever increasing human population. However, these strategies are complicated, laborious and require more cropping area for parental increase and maintenance including employment of sophisticated backcross breeding for line conversion and search for suitable restorers. The biotechnological methods (BMS) simplified the strategies each in its own approach, though having certain disadvantages too as for example, dual component Barnase/Barstar and Cystein protease/Cystatin approach needed herbicidal spray. The next generation hybrid breeding systems were developed utilising GMS system under nuclear control avoiding search for suitable restorers and cytoplasm-nuclear interactions. The era of genomics assisted breeding has facilitated well characterised study of several crop genes including male fertility genes which is a never ending approach. In combination with transgenic and genome editing approaches, the next generation hybrid breeding systems such as “Seed Production Technology” (SPT), “Multi Control Sterility” (MCS) and “MGM-Maintainer approach” have provided easy and well defined mode of utilising male sterility for hybrid seed production bypassing all the complications of traditional techniques.