LIFE SCIENCE

Detailed explanation-1: -The nod genes are the key bacterial determinants of the signal exchange between the two symbiotic partners. The product of the nodD gene is a transcriptional activator protein that functions as receptor for a flavonoid plant compound.

Detailed explanation-2: -The common nodABC genes, present in all Rhizobium species, are required for the synthesis of the core structure of NFs. NodC is an N-acetylglucosaminyltransferase, and NodB is a chitooligosaccharide deacetylase; NodA is involved in N-acylation of the aminosugar backbone.

Detailed explanation-3: -Purified bacterial signal molecules, the nodulation factors (NFs), which are lipochitooligosaccharides, induce root hair deformation in the appropriate host legume and have been proposed to be a key player in eliciting root hair curling.

Detailed explanation-4: -Nodulin genes include genes encoding enzymes of nitrogen and carbon metabolism. A gene encoding uricase is a soybean nodulin, and a gene encoding glutamine synthetase is a nodulin in many other species. 2. The gene encoding the leghemoglobin apoprotein also is a nodulin and is expressed only in nodules.