Change bottom border color of selected tab bar item

I have the following code in react-native

import React, {Component} from 'react';
import {TabNavigator} from 'react-navigation';
import {View} from 'react-native';

class Home extends Component {

  static navigationOptions = {
        title:'Home',
        tabBarLabel:'First'
  };

  render() {
    return <View></View>;
  }

}

const tabOptions = {

    tabBarOptions: {
        activeTintColor:'white',
        inactiveTintColor:'#D3D3D3',
        style:{
            backgroundColor:'green',
            borderTopWidth:1,
            borderTopColor:'#D3D3D3'
        },
        tabBarSelectedItemStyle: {
            borderBottomWidth: 2,
            borderBottomColor: 'red',
        },
    },
}

const ProductNavigator = TabNavigator({
  First: {screen: Home},
  Second:{screen: Home}
},
tabOptions
);
export default ProductNavigator;

This is what it looks like when rendered in Android emulator

I want the yellow underline to be RED underline instead. But my rules for tabBarSelectedItemStyle that declare a red underline are not being acknowledged. How do I make the underline of selected tab bar items to be red?

To style TabNavigator selected item's indicator you can use indicatorStyle.

indicatorStyle - Style object for the tab indicator (line at the bottom of the tab).

Example

const tabOptions = {    
    tabBarOptions: {
        activeTintColor:'white',
        inactiveTintColor:'#D3D3D3',
        style:{
            backgroundColor:'green',
            borderTopWidth:1,
            borderTopColor:'#D3D3D3'
        },
        indicatorStyle: {
            backgroundColor: 'red',
        },
    },
}

const ProductNavigator = TabNavigator({
  First: {screen: Home},
  Second:{screen: Home}
}, tabOptions);