## 3 Results
### Nitrogen-Fixing Genes
#### 3.7.6 Heat and Cold Stress Genes  
Well represented from our study are the cold and heat stress genes _cspABCDEFG_, _groEL_ and _groES_ (Table 4, Figure 10). _cspA_ had a relative abundance of 898 for R1, 557 for R2, and 616 and 653 for B1, and B2, respectively. _cspB_ had a relative abundance of 166 and 63 for both R1 and R2, while B1 and B2 had a relative abundance of 93 and 128, respectively. _cspC_ had 456 for R1, 319 for R2, 312 for B1, and 341 for B2. The heat shock protein chaperone with aliases _groEL_ had a relative abundance of 7318 in R1, 4453 in R2 metagenome, 4977 in B1 and 5603 in B2, while co-chaperone _groES_ gene had 1409 for R1, 814 for R2, 1016 for B1 and 1134 for B2. _CspABCEG_ was more abundant in the rhizosphere than the bulk soils, although rhizosphere location R1 was more enriched than R2.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Genes**} & \multirow{2}{*}{**Biological Functions**} & \multirow{2}{*}{**Aliases**} & \multicolumn{2}{c}{**Relative**} & \multirow{2}{*}{} & \multirow{2}{*}{} \\  & & & **Abundance** & & & \\  & & & & **of Genes** & & & \\ \hline \multirow{3}{*}{Nitrogen fixation} & \multirow{3}{*}{C cysteine desulfurase _nifS_} & \multirow{3}{*}{EC 2.8.1.7 _nifS_} & R1 & R2 & B1 & B2 \\  & & & 2.8.1.7 _nifS_ & 94 & 19 & 44 & 69 \\  & & & 2.8.1.7 _sufS_ & 395 & 211 & 262 & 272 \\  & & & & & & \\  & (molybdenum-iron) & \multirow{3}{*}{_nifH_} & \multirow{3}{*}{6} & \multirow{3}{*}{5} & \multirow{3}{*}{1} & \multirow{3}{*}{0} \\  & reductase and maturation & & & & & \\  & & & & & & \\  & protein _nifH_ & & & & & \\  & 2,3-dihydro-2,3- & EC 1.3.1.28 & & & & \\ Siderophore & dihydroxybenzoate & bacillibactin & & & & \\  & dehydrogenase & 2,3-dihydro-2,3- & EC 1.3.1.28 & & & \\  & dihydroxybenzoate & enterobactin & & & & \\  & dehydrogenase & & & & & \\  & ABC Fe3+ siderophore & & & 73 & 112 & 58 & 43 \\  & transporter & & & & & \\  & Ferric siderophore & & & & & \\  & transport system, & & & & & \\  & biopolymer transport & _exbB_ & 146 & 116 & 110 & 103 \\  & protein _exbB_ & & & & & \\  & Aerobactin siderophore & & & & & \\  & receptor _IutA_ & & 2 & 7 & 3 & 2 \\  & Iron siderophore receptor & & & 9 & 2 & 6 & 10 \\  & protein & & & & & \\  & TonB-dependent & & & & & \\  & siderophore receptor & & & & & \\  & 1-aminocyclopropane-1- & & & & & \\ ACC deaminase & carboxylate deaminase & EC 3.5.99.7 & 599 & 395 & 371 & 400 \\  & _acdS_ & & & & & \\  & Exopolysaccharideacharide & Biosynthesis & _epsF_ EC 2.4.1.- & 80 & 48 & 74 & 80 \\  & glycosyltransferase _epsF_ & & & & & \\  & Exopolysaccharideacharide & & & & & \\  & production protein _exoF_ & _exoF_ & 17 & 3 & 4 & 2 \\  & precursor & & & & & \\  & Exopolysaccharide & & & & & \\  & production protein _exoZ_ & _exoZ_ & 38 & 45 & 24 & 39 \\  & Exopolysaccharide & & & & & \\  & biosynthesis & & & & & \\  & transcriptional activator & _epsA_ & 4 & 3 & 3 & 3 \\  & _epsA_ & & & & & \\ High-temperature & Protease/chaperone & & & & & \\ stress response & protein _htrA_ & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 4: Relative abundance of plant growth functional genes as observed in sunflower rhizosphere (R1, R2) and bulk (B1, B2) soil samples.