push(@{$hash->{$fields[0]}}, \@genes);

##</code><code>##

push(@{$hash->{$fields[0]}}, @genes);

##</code><code>##

$VAR1 = {
          'malZ' => [
                      'b0403'
                    ],
          'malS' => [
                      'b3571'
                    ],
          'manA' => [
                      'b1613'
                    ],
          'malXY' => [
                       'b1621',
                       'b1622'
                     ],
          'malT' => [
                      'b3418'
                    ]
        };